Method of cleaning an inner wall of a mold by means of dry ice

ABSTRACT

A method for cleaning an inner wall of a mold part includes forming a chamber between displaced mold parts by introducing a casing between the mold parts. The casing enclosures a blasting device for introducing a blasting nozzle which directs a cleaning jet at the inner wall. The chamber encapsulates noise and particles which are produced during the cleaning process.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject matter of the invention includes a method and an apparatusfor cleaning an inner wall of a mold. In particular, the presentinvention includes a method and apparatus for cleaning an inner wall ofa mold for producing vehicle tires, by means of dry-ice pellets.

2. Related Art

An extremely wide range of cleaning methods are known for the purpose ofcleaning metallic components. The cleaning methods may be subdividedinto physical and/or chemical cleaning methods. The chemical cleaningmethods are based on the particles of dirt which adhere to the componentbeing subjected to a chemical reaction by the action of a cleaning agentand being detached from the component as a result. Special apparatuses,which are complex and very expensive, are necessary for carrying outchemical cleaning. As a result of the generally aggressive cleaningmedia, only high-quality, chemically resistant materials can be used insuch cleaning apparatuses. Cleaning apparatuses which operate on achemical basis are also subject to stringent legal regulations which canonly be met by considerable outlay on equipment.

As an alternative to chemical cleaning, components may be cleaned byphysical methods. In this case, the contaminants are removedmechanically from the component by abrasion. Abrasive media may be usedfor removing contaminants from a component. Abrasive media may be in theform of sand, cork or glass. Probably best-known method of mechanicallyremoving contaminants from a component is the so-called sand-blastingmethod. Sand blasting is preferably carried out in separate chambers, inwhich the component is introduced and blasted by a sand-blasting device.

DE 43 14 264 C1 discloses a sand-blasting device which is suitable forcleaning rims of motor-vehicle wheels. The motor-vehicle rim which is tobe cleaned is arranged in a housing, the base of which is of funnel-likedesign. The funnel-like base of the housing is connected to asand-collecting area by a connecting duct. The sand-collecting area isconnected to the sand-blasting device via a sand-feed line. Thesand-blasting device may be located in the housing. According to DE 4314 264 C1, it is possible for only the front, nozzle-like end of thesand-blasting device to project into the housing. This configuration ofthe apparatus for cleaning rim of motor-vehicle wheels minimizes thesand consumption since the cleaning sand runs around in a closedcircuit.

In addition, U.S. Pat. No. 4,603,515 discloses a means for removing alayer of corrosion from the walls of the booster of a bomb. The layer ofcorrosion is removed by sand blasting. In order to remove the sand fromthe shell of the bomb, a vacuum means is provided.

Sand-blasted components subsequently have to be subjected to carefulcleaning in order to ensure that the fine sand is removed from allpossible niches of the component. The use of sand blasting for cleaningmolds, in particular molds for producing plastic parts, is very costlybecause of the relatively high cost outlay for cleaning, which isnecessary in order to remove the sand from all possible niches of themold. The possible ways of cleaning components which have been describedabove require that the component which is to be cleaned is providedseparately. In the case of molds of plastic-processing machines or moldsfor producing vehicle tires, then it is necessary for the mold to beremoved from the machine. Once the cleaning operation has been carriedout, the machine has to be set up anew. This procedure for cleaningmolds is costly and results in the operating time of the machine beingreduced considerably.

In order to avoid the removal and reinstallation of a mold, it is alsoknown for such molds to be cleaned manually. This method of cleaning ishazardous to the personnel carrying out the cleaning since aerosols areproduced during the cleaning operation, which may have an adverse effecton health if suitable protective measures are not provided for thepersonnel. In addition, cleaning of the inner wall of the mold can bedifficult due to a multiplicity of narrow and short depressions.

It is also known for components to be cleaned by means of dry-icepellets. Dry ice is carbon dioxide which has been converted into thesolid physical state. Under atmospheric pressure, dry ice changesdirectly from the solid physical state into the gaseous state withoutany melt liquid being produced. Cleaning with dry ice thus has theadvantage that no residues of the dry ice remain in the mold. With theaid of a carrier medium, e.g. air or nitrogen, the dry-ice pellets areblasted, via a cleaning nozzle, against the component which is to becleaned. The pellets remove the contaminants from the wall of acomponent. The mechanical removal of the contaminants is assisted by therefrigerating action of the dry ice, which is at a temperature of atleast -78.5° C. During cleaning there is a high emission of sound. Thesource of the sound emission is the cleaning nozzle, through which thecleaning jet which contains dry-ice pellets emerges. A reduction in thesound emission at the cleaning nozzle has been achieved by a furtherdevelopment of the cleaning nozzle. However, the sound emission is stillof such a magnitude that cleaning of a component can only be carried outif costly sound-insulation measures are taken.

OBJECTS AND SUMMARY

An object of the present invention is to specify a method and anapparatus for cleaning an inner wall of a mold which allow the molds tobe cleaned with at a low cost. In particular, the intention is tospecify a possible way of cleaning which does not require the mold to beremoved from its associated machinery. Therefore, the production processis not disrupted by the cleaning operation. The invention isparticularly applicable to molds of vehicle tires.

The invention includes an inventive method of cleaning an inner wall ofat least one part of a two part mold, each part can be displacedrelative to one another along an axis and, in a closed state, form acomplete mold. The mold is preferably a mold of a plastic-processingmachine. The inventive method is particularly useful for cleaning theinner wall of a mold used for producing tires. According to a method ofthe invention, when the mold parts are spaced apart from one another inan open state, a casing and a movable blasting device are introducedbetween the mold parts. A chamber which is bounded by the casing and themold parts are then formed. Once the chamber has been formed, a cleaningjet which contains dry-ice pellets and a carrier medium is introduced.The cleaning jet emerges from a blasting nozzle of the blasting device.At least the blasting nozzle of the blasting device is moved, so thatthe cleaning jet is directed against parts of the surface of the innerwall. The formation of the chamber considerably reduces sound emissionduring the cleaning operation since the casing and the mold partstogether effect encapsulation of the sound which is produced duringcleaning. Any adverse effects on the surroundings are consequentlyreduced to such an extent that cleaning of the mold can take placedirectly at the machine without any adjacent processes being disrupted.The way of implementing the method according to the invention makes itpossible for the inner wall to be cleaned without there being any needfor the mold to be removed from the machine. Cleaning can thus takeplace on site. This achieves cost-effective cleaning of the mold since,in contrast with the method known up until now, there is no need for anylabor-intensive work to be carried out. Furthermore, there is areduction in the downtime of the machine, which means the machine isbetter utilized.

The distance between the mold parts when the mold is in the open statecannot be varied at will. This distance is predetermined by the designof the machine. In order for it to be possible to introduce the casingcomfortably between the mold parts, the casing is preferably collapsedor folded such that its height is smaller than the distance between theopen mold parts. In order to form the chamber, it is thus proposed thatthe casing be telescoped, with the result that it butts against therelevant mold part by way of its respective end regions.

According to a further aspect of the invention, it is proposed thatsealing of the chamber be achieved by the casing which butts against therelevant mold part by way of its respective end regions. Amachine-control means allows displacement of at least one mold partalong an axis, and that the casing has a certain degree of stiffness.

According to a further advantageous embodiment of the invention, it isproposed that a cage-like framework, on which the casing is secured, beintroduced between the mold parts. The framework has an annular bottompart and an annular top part as well as spacers. The spacers areconnected to the bottom part and the top part. The spacers aretelescoping and permit the top and bottom parts to engage the relevantmold part. Alternatively, it is possible to displace at least one of themold parts along the axis, with the result that the bottom part and thetop part of the framework and/or the casing, by way of its respectiveend regions, butt/butts against the relevant part-mold.

Telescoping of the spacers has the advantage that, in the case ofmachines whose machine-control means allow for just two mold states,namely an open state and a closed state, the bottom part and the toppart can be made to butt against the respective mold part without therebeing any need for activation of the machine-control means. Thisembodiment of the invention is also advantageous in the case of machinesin which the displacement path of at least one mold part is to becontrolled manually. Since it is not necessary to move the mold parts toengage the casing/framework, any carelessness of the operating personnelwhich may damage the casing/framework is avoided.

It is proposed, according to a further advantageous embodiment, that therespective end regions of the casing and/or the bottom part and the toppart be connected to the relevant mold part in an air-tight manner.

In order to reduce any adverse effects caused by aerosols, it isproposed, that the particles detached from the inner wall of the mold befiltered out through a partially gas-permeable casing. It is preferablethat the particles be filtered out through a particle filter integratedin the casing.

An inner wall of a mold is preferably cleaned by directing the cleaningjet against the entire inner wall in a stepwise manner. In this way theconsumption of the dry-ice pellets and of the carrier medium is low. Itis preferable here for the cleaning jet to be displaced continuously.

The degree to which a mold is contaminated may differ in differentregions of the mold. It is thus proposed that the cleaning jet bedirected against individual sections of the inner wall one after theother. In this case, the cleaning jet can pass over a section of theinner wall a number of times. The movement of the cleaning jet ispreferably positively controlled.

The inventive apparatus for cleaning an inner wall of at least one moldpart of a two part-mold is distinguished by a casing, a movable blastingdevice and a supply unit. The movable blasting device has at least oneblasting nozzle from which there emerges a cleaning jet which isdirected against at least part of the surface of the inner wall andcontains dry-ice pellets and a carrier medium. The blasting device isconnected to the supply unit via at least one supply line, the supplyunit providing the dry-ice pellets and a carrier medium. The carriermedium is preferably compressed air. The casing and the blasting deviceof the apparatus according to the invention can be introduced betweenthe mold parts. The casing and the mold parts define a chamber duringthe cleaning operation. This chamber, which is partially bounded by theintegral components of the mold which is to be cleaned, forms a meansfor encapsulating sound. The encapsulation of the sound achieves aconsiderable reduction in sound emission during cleaning. As a result,it is possible for the mold to be cleaned without the latter having tobe removed from its associated machinery. A further advantage of theapparatus is that cleaning of the mold can also be carried out withoutinterruption in production and operation of the machinery. This designof the apparatus also reduces the cleaning costs since there, is areduction in the downtime of the machine.

According to an advantageous aspect of the apparatus, it is proposedthat the casing be of flexible design. The flexible configuration of thecasing means that it is easier for the latter to be introduced betweenthe mold parts, as a result of which the apparatus is easier to handle.

Encapsulation achieves a reduction in the sound emission. In order toreduce this further, it is proposed that the casing be ofsound-insulating design. For this purpose, the casing preferably has asound-insulating structure. As a supplement or alternative to asound-insulating casing structure, said casing preferably has asound-insulating coating.

The casing and/or the bottom part and the top part of the frameworkpreferably has/have an elastic seal. These seals can be made to buttagainst the relevant mold part. The elastic seal ensures that no gap isproduced between the casing and/or the top part and the bottom part ofthe framework and the respective mold part through which sound canemerge from the chamber. A further advantage of the elastic seal can beseen in the fact that the seal correspondingly fits closely against themold parts. Therefore, the casing and/or of the bottom part and of thetop part of the framework do not have to precisely conform to thesurface(s) of the mold parts.

The cleaning jet contains dry-ice pellets and a carrier medium. Thecarrier medium is preferably compressed air. In the case of anessentially air-tight configuration of the chamber, there would be abuild-up of pressure within this chamber and, in some circumstances,this build-up of pressure would result in the casing being destroyed. Inorder to avoid this, it is possible for the casing to be at leastpartially gas-permeable. The mold may also have material-feed openingsand air-extraction bores connected to the surroundings. In the event ofa build-up of pressure in the chamber, flow from the chamber through thematerial-feed openings and air-extraction bores to the surroundingswould occur. This gas flow would also entrain particles which, in somecircumstances, would result in blockage of the openings. In order toavoid this, an at least partially gas-permeable design of the casing ispreferred. The casing, which is at least partially gas-permeable, isconfigured such that it is impermeable to particles. This ensures thatthe particles of dirt detached during the cleaning operation are notblown into the surroundings.

The casing preferably has a particle filter which is exchangeable. Theparticle filter retains in the filter the particles of dirt detachedduring cleaning, as a result of which any adverse effects on thesurrounding atmosphere caused by the cleaning operation are avoided. Thecapacity of the particle filter to be exchanged enhances theavailability of the apparatus since cleaning of the casing is notabsolutely necessary.

The casing is preferably of essentially zigzag-shaped design incross-section. It can thus be collapsed and telescoped in the manner ofan accordion. Preferably, the casing is of essentially tubular orbellows-like design.

The molds whose interior are to be cleaned by the apparatus according tothe invention may be of an extremely wide range of configurations andstructures. The cleaning nozzle preferably directs the cleaning jetagainst the inner wall of the mold such that the entire inner wall iscleaned in a stepwise manner. In order to achieve this, the apparatushas a handling means on which the cleaning nozzle is or nozzles is (are)arranged. The handling means permits a local change in a cleaning jetemerging from a cleaning nozzle, with the result that the entire innerwall is cleaned by the cleaning jet, which contains dry-ice pellets.With knowledge of the configuration of the inner wall, the movement ofthe cleaning nozzle can be controlled by means of a correspondingcontrol unit. The control unit causes the cleaning nozzle to sweep overindividual sections of the inner wall continuously or one after theother. In the case of more straightforward molds, it is expedient, insome circumstances, to change the position of the cleaning nozzle, andthus of the cleaning jet, manually. Manual operation is suitable, inparticular, when the frequency of mold cleaning is relatively low.Automated cleaning of the mold, however, is preferable since thecleaning times and cleaning action can be optimized by the positivelycontrolled movement of the cleaning nozzle. Optimization of the cleaningaction and of the cleaning times results, inter alia, in a reduction inthe consumption of dry-ice pellets. Therefore, the costs of the cleaningoperation can be minimized. In addition to the lower costs for cleaning,there is a reduction in the cost of equipment for providing largequantities of dry ice.

According to a further advantageous aspect of the apparatus, it isproposed that the handling means has a central unit and at least one armwhich is connected to the central unit, and on which the blasting unitis arranged. The central unit is arranged outside the chamber, the armextending through the casing.

The central unit and the supply unit are arranged on a transportableload-bearing structure. From the aspect of safety, it is proposed thatthe load-bearing structure has a protective housing in which the centralunit and the supply unit are arranged.

For the purpose of positioning the load-bearing structure on a machinewhose mold is to be cleaned, it is proposed that the load-bearingstructure have a positioning means.

According to a further advantageous aspect, it is proposed that thecasing be arranged on a cage-like framework, the framework having anannular bottom part and an annular top part as well as spacers which areconnected to the bottom part and the top part. The cage-like frameworkand the casing are designed such that the bottom part and the top partand/or the casing, by means of its respective end regions, can be madeto butt against the relevant mold part. For this purpose, it is proposedthat the spacers be of a telescopic configuration. The capacity of thespacers to telescope can be achieved in that said spacers are formed bycylindrical members.

The casing preferably encloses the framework. The casing may beconnected to the framework in a releasable manner.

According to a further preferred configuration of the apparatus, it isproposed that the handling means be arranged within the space bounded bythe framework. As a result, the framework, along with the casing and thehandling means, is introduced between the mold parts. The handling meansis preferably a six-axis robot. In the case of a further configurationof the apparatus, the handling unit is arranged on a carrying ring whichcan be rotated about a longitudinal axis of the framework. Duringcleaning, rotation of the carrying ring can position the handling meanswithin the chamber. The carrying ring is preferably arranged on thebottom part in a rotatable manner. For precise positioning of thecarrying ring within the chamber, it is proposed that the bottom parthave a toothing arrangement with which a gear wheel arranged on a driveshaft of a drive can be brought into operative connection, the drivebeing arranged on the carrying ring in a stationary manner. The drive ispreferably a stepping motor. If appropriate, a gear mechanism may bearranged between the drive shaft and the drive.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Further advantages and details of the method of, and of the apparatusfor, cleaning an inner wall of a mold are explained with reference todrawing figures in which:

FIG. 1 shows a schematic view of a first exemplary embodiment of acleaning apparatus,

FIG. 2 shows a schematic view of a framework on a part-mold,

FIG. 3 shows a schematic view of a carrying ring with a handling means,

FIG. 4 shows a perspective view of an apparatus with a top part-mold,

FIG. 5 shows an apparatus as in FIG. 4 but with a bottom part-mold, and

FIG. 6 shows a schematic view of another exemplary embodiment of acleaning apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a schematic view of a first exemplary embodiment of anapparatus for cleaning an inner wall of a mold. The mold which isillustrated in FIG. 1 is a mold for producing tires. The mold has a topmold part 1 and a bottom mold part 2. The top mold part 1 is designed tobe displaceable along the axis A. The top mold part 1 and the bottommold part 2 are arranged in a machine 25. In the state which isillustrated in FIG. 1, the mold is open. For the purpose of cleaning aninner wall 14 of the top mold part 1 and/or of the bottom mold part 2,an apparatus which has a casing 3 is provided. The casing 3, as can beseen from FIG. 1, is of zigzag-shaped, essentially tubular design. Thecasing 3 is flexible. It has sound-insulating properties. Furthermore,the casing 3 is at least partially gas-permeable. In particular, it isdesigned wholly or partially as a particle filter 35, or is providedwith a particle filter 35.

The casing 3 is arranged between the mold parts 1 and 2. The casing 3and the mold parts 1, 2 define a chamber 9. The end region 5 of thecasing 3 butts against the outer wall of the mold part 1. The other endregion 6 of the casing 3 butts against the mold part 2. A fasteningdevice 26 is provided for air-tight attachment of the end region 5 ofthe casing 3. A corresponding fastening device 27 is provided at the endregion 6.

A blasting device 4 which has at least one blasting nozzle 8 is arrangedin the chamber 9. Emerging through the blasting nozzle 8, against atleast part of the surface of the inner wall 14, is a cleaning jet 7which contains dry-ice pellets and a carrier medium. The blasting device4 is connected to a supply unit 15 via supply lines (not illustrated).The supply unit 15 preferably comprises a supply container with dry-icepellets and a compressed-gas source, which may be, for example, a gascylinder.

The blasting device 4 is arranged on a handling device 16. The handlingdevice 16 is preferably a multi-axis robot. The handling device 16 has acentral unit 17 which is connected to an actuating arm 18. The centralunit 17 is arranged outside the chamber 9. The arm 18 ,extends into thechamber 9. Connected to the arm 18 is a connecting plate 28, which isalso connected to the casing 3.

The supply unit 15 and the central unit 17 are arranged on atransportable load-bearing structure 19. The load-bearing structure 19has a housing 20 in which the central unit 17 and the supply unit 15 arearranged. The load-bearing structure 19 also has a positioning device21, which can be brought into contact with the framework of the machine25, as a result of which the structure 19 assumes a predeterminedposition with respect to the machine 25.

An apparatus for cleaning an inner wall 14 of at least one mold part 1,2, which is illustrated in FIG. 1 operates as follows:

Once the mold part 1 has been displaced along the axis A, the casing 3and the blasting device 4 are introduced between the mold parts 1, 2.The end regions 5, 6 of the casing 3 are made to butt against the moldparts 1, 2, respectively. There is preferably an air-tight connectionbetween the end region 5 and the mold part 1 and between the end region6 and the mold part 2. The casing 3 and the mold parts 1, 2 define achamber 9. The inner wall 14 of the mold part 1, 2 is blasted by theblasting nozzle 8 of the blasting device 4. For this purpose, theblasting device 4 is moved appropriately. The blasting device 4 is movedby the handling device 16.

FIGS. 2 to 5 show parts of a further embodiments of an apparatus forcleaning an inner wall 14 in at least one mold part 1, 2 of a mold.

FIG. 2 illustrates a mold part 1 on which a cage-like framework 10 isarranged. The cage-like framework 10 has an annular bottom part 11 andan annular top part 12. The bottom part 11 and the top part 12 areconnected to one another by spacers 13. In the exemplary embodimentillustrated, the spacers 13 are arranged in an equidistant manner withrespect to one another as seen in the circumferential direction. Thespacers 13 are preferably profile bars. A casing 3 (not illustrated) maybe arranged on the cage-like framework. A guide rail 29 is arranged onthat surface of the bottom part 11 which faces the top part 12. Thefunction of the guide rail 29 will be discussed in more detail below.The bottom part 11 also has a toothed rim with an internal toothingarrangement 23.

A carrying ring 22, as is illustrated in FIG. 3, may be arranged withinthe framework 10. On its bottom surface, the carrying ring 22 has guiderollers 30, which are guided along the guide rail 29 of the bottom part11. A handling device 16 is arranged on the top side of the carryingring 22. Furthermore, the carrying ring 22 has a drive 24, which has adrive shaft with a gear wheel (not illustrated) which engages in thetoothing arrangement 23 of the bottom part 11. By virtue of the drive 24being actuated, the carrying ring 22 can be rotated relative to theframework 10. The drive 24 is preferably a stepping motor. FIG. 3 alsoshows that rollers 31 are provided on the top side of the carrying ring22, said rollers being distributed over the circumference of animaginary circle. The rollers 31 serve for receiving a so-calledenergy-management chain (not illustrated) by way of which theconsumables are fed from the supply unit to the handling unit 16 and theblasting device 4. A guide 32 is provided for guiding theenergy-management chain.

FIG. 4 illustrates the framework 10 according to FIG. 2 with thecarrying ring 22 and the components arranged thereon according to FIG.3. The handling unit 16 has a blasting device 4, which has a nozzle (notindicated specifically) through which a cleaning jet is directed againstthe inner wall 14 of the part-mold 2. Rotation of the carrying ring 22can position the handling unit 16 in the circumferential direction.

As can be seen from FIG. 4, the top part 12 butts against the endsurface 33 of the mold part 2. The inner wall 14 of the mold part 2 canbe cleaned in its entirety by virtue of the handling device 16 and thecarrying ring 22 being moved. For the sake of clarity, the casing 3,which is arranged on the framework 10, has not been illustrated in FIG.4. FIG. 5 illustrates a different position of the blasting device 4. Theblasting device 4 is directed against the bottom mold part 1, as aresult of which a jet 7 can clean the inner wall 14 of the mold part 1.As far as any further details of the apparatus are concerned, referenceis made to the description of FIGS. 2, 3 and 4.

An apparatus for cleaning an inner wall 14 of at least one mold part 1,2, is illustrated in FIGS. 2 to 5 operates as follows:

The framework 10 and the casing 3, which is not illustrated arepositioned between the mold parts 1 and 2. At least one of the moldparts 1, 2 is (are) displaced such that the top part comes into contactwith the end surface 33 of the mold part 2 and the bottom part 11 comesinto contact with the end surface 34 of the mold part 1. As can be seenfrom FIGS. 4 and 5, the top part 12 butts against the end surface 33 ofthe mold part 2 and the bottom part 11 butts against the end surface 34of the mold part 1. This produces an air-tight connection between themold part 2 and the top part 12, and between the mold part 1 and thebottom part 11. A casing 3 (not illustrated) encloses the framework 10.The framework 10, with the casing 3, and the mold part 1 and the moldpart 2 together define a chamber 9, in which the handling device 16 andthe blasting device 4 are arranged. The cleaning operation may then becarried out, in which case a cleaning jet 7, which contains dry-icepellets and compressed air, is directed against the wall 14 in astepwise manner. Once cleaning has been completed, the connectionbetween the mold part 1 and the mold part 2, and the framework 10 isreleased, and the framework 10 with the handling device 16 is removedfrom the other components in the space between the mold part 1 and themold part 2.

FIG. 6 shows another exemplary embodiment of an apparatus for cleaningan inner wall of a mold. The mold has a top mold part 1 and a lower moldpart 2. The top mold part 1 and the bottom mold part 2 are designed tobe displaceable relative to one another along the axis A. The top moldpart 1 and the bottom mold part 2 form part of a machine 25. FIG. 6shows an open mold, i.e.--the mold part 1 and the mold part 2 have beendisplaced relative to one another, in opposite directions, along theaxis A.

An apparatus which has a casing 3 is provided for the purpose ofcleaning an inner wall 14 of the top mold part 1 and/or of the bottommold part 2. The casing 3 is of an essentially hollow-cylindricaldesign. It preferably is constructed of a flexible material. In order toreduce sound emission during a cleaning operation, the casing 3 hassound-insulating properties. Furthermore, the casing 3 is at leastpartially gas-permeable. The casing 3 is preferably designed wholly orpartially as a particle filter 35, or is provided with a particle filter35.

At its mutually opposite end regions, the casing 3 is connected to abottom part 11 and a top part 12. The bottom part 11 and the top part 12are of essentially plate-like design. The bottom part 11 has an opening36 and the top part 12 has an opening 37. The opening 37 of the top part12 is dimensioned such that it exposes the cross section of the openingof the top mold part 1. In the exemplary embodiment illustrated in FIG.6, the bottom mold part 2 extends through the opening 36. The top part12 and the bottom part 11 butt against the relevant mold parts. Thecasing 3 is connected to the bottom part 11 and the top part 12.

A blasting device 4, which has at least one blasting nozzle 8, isarranged in the chamber 9. Emerging through the blasting nozzle 8against at least part of the surface of the inner wall 14 of the topmold part 1 and/or bottom mold part 2, is a cleaning jet which containsdry-ice pellets and a carrier medium. The blasting device 4 is connectedto a supply unit 15 via supply lines 38. The supply unit 15 preferablycomprises a supply container with dry-ice pellets and a compressed-gassource, which may be, for example, a gas cylinder.

The blasting device 4 is arranged on a handling device 16. The handlingdevice 16 can be a multi-axis robot. The multi-axis robot is configuredsuch that the cleaning jet 7 can clean the entire inner wall 14 of amold. For this purpose, the multi-axis robot is preferably a six-axisrobot. The handling device 16 has a central unit 17 which is connectedto the handling device 16 via supply lines 38. The central unit 17 formsa control unit for the handling device 16. The handling device 16 isarranged in the chamber 9 in a stationary manner. It is connected to aconnecting plate 38, which forms part of the wall of the chamber 9.

The supply unit 15 and the central unit 17, and preferably the casing 3,with the handling device 16, are arranged on a transportableload-bearing structure 19.

The functioning of that embodiment of an apparatus for cleaning an innerwall of at least one part-mold which is illustrated in FIG. 6corresponds essentially to the functioning of that embodiment of anapparatus which is illustrated in FIG. 1.

Only preferred embodiments of the invention are specifically illustratedand described herein. It should be appreciated that the numerousmodifications and variations of the present invention are possible inlight of the present disclosure, such modifications and variations beingencompassed within the scope of the appended claims without departingfrom the spirit and scope of the invention.

I claim:
 1. A method of cleaning an inner wall of at least one mold partof a mold having at least two parts which can be displaced relative toone another along an axis and, in a closed state, form a complete mold,comprising the steps of:creating a displacement along the axis betweenthe two mold parts; introducing a casing and a movable blasting devicebetween the mold parts; forming a chamber which is bounded by the casingand the mold parts; producing a cleaning jet which comprises dry-icepellets and a carrier medium from a blasting nozzle of the blastingdevice and; moving at least the blasting nozzle such that the cleaningjet comes into contact with at least part of a surface of the innerwall.
 2. The method according to claim 1, comprising telescoping thecasing such that the casing butts against at least one of said moldparts at respective end regions of the casing.
 3. The method accordingto claim 1, comprising displacing at least one of said mold parts alongthe axis such that the casing butts against at least one of said moldparts at respective end regions of the casing.
 4. The method accordingto claim 1, comprising introducing a cage-like framework, on which thecasing is secured, between the mold parts, the framework having anannular bottom part and an annular top part as well as spacers which areconnected to the bottom part and the top part, and telescoping thespacers along the axis such that the bottom part and the top part buttagainst at least one of said mold parts.
 5. The method according toclaim 1, comprising forming an air-tight connection between respectiveend regions of the casing and the mold parts.
 6. The method according toclaim 1, comprising at least partially filtering out particles detachedfrom the inner wall by constructing the casing to be at least partiallygas permeable.
 7. The method according to claim 1, comprising at leastpartially filtering out particles detached from the inner wall through aparticle filter.
 8. The method according to claim 1, comprisingdirecting the cleaning jet against the inner wall in a continuousstepwise manner.
 9. The method according to claim 1, comprisingdirecting the cleaning jet against a first individual section of theinner wall such that said cleaning jet passes over said first individualsection one or more times before being directed against a secondindividual section of said inner wall.